Top Definition
LSI
Laughing Silently Internally . This acronym is meant to take the place of LOL which stands for Laughing Out Loud. It is my belief, and I think I can speak for millions of others, that the acronym LOL is overused and not meaningful. People have overused it as a quick and easy way to say that they find something funny. They are probably not really laughing out loud. LSI is a way to quickly say that you find something funny but being truthful. Now when you say LOL it will have even more meaning.
example: a facebook post
This video is so funny. LSI.

example a response to text message
You are retarded! LSI

As an adjective:
I was checking out this blog and it was funny. Had me LSIing

now you can use LOL when more appropriate:
When you told me you were destined for greatness you had me LOL. I was drinking a cola at the time and shot right out of my nose!
by The Stroz January 15, 2014

The Urban Dictionary Mug

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The Urban Dictionary Mug

Lotsa space for your liquids.

Buy the mug

The Urban Dictionary Mug

Your favorite word on a white mug.

Create a mug

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

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The Urban Dictionary T-Shirt

Soft and offensive. Just like you.

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The Urban Dictionary T-Shirt

Smooth, soft, slim fit American Apparel shirt. Custom printed. 100% fine jersey cotton, except for heather grey (90% cotton).

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LSI
Life Saving Instructor. A Person who is able to instruct lifesaving courses
With my LSI I was able to teach Bronze cross.
by GSS_NS November 08, 2006

The Urban Dictionary Mug

Lotsa space for your liquids.

Buy the mug

The Urban Dictionary Mug

Lotsa space for your liquids.

Buy the mug

The Urban Dictionary Mug

Your favorite word on a white mug.

Create a mug

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug

The Urban Dictionary T-Shirt

Soft and offensive. Just like you.

Buy the t-shirt

The Urban Dictionary T-Shirt

Smooth, soft, slim fit American Apparel shirt. Custom printed. 100% fine jersey cotton, except for heather grey (90% cotton).

Buy the t-shirt